Due to the anisotropic characteristics of liquid crystal material, a liquid crystal device usually only responds to polarized light. So when a crystal liquid lens is applied or used in an imaging device, a polarizing device such as a polarizing plate or a polarizer is required to polarize incident light. But the use of the polarizing plate or polarizer may lower the light intensity to less than half of the initial incident light intensity. Thus, in a darker or low light environment, there may be not enough light to reach the image sensor, causing decreased signal to noise ratio and lowered image quality.
To avoid the use of the polarizing plate or polarizer, a lens group composed of multiple superimposed liquid crystal lenses with their initial alignment of the liquid crystal layers perpendicular to each other may be used in the imaging system. Or a liquid crystal lens superimposed by multiple liquid crystal layers with their initial alignment perpendicular to each other may be designed for the imaging system. Each liquid crystal lens or each crystal liquid layer processes respectively polarization component of an arbitrary polarization state in two perpendicular directions, thus it can be applied to process arbitrary polarization state. But the solution may have the following problems.
For the solution with multiple superimposed liquid crystal lenses or multiple superimposed liquid crystal layers, due to the increased number of the liquid crystal lenses or liquid crystal layers, the manufacturing cost of the liquid crystal lens may be greatly increased. The increased number of liquid crystal lenses or liquid crystal layers may also greatly increase the thickness of the device, making it difficult for the liquid crystal lens imaging apparatus to be integrated into mobile devices such as mobile phones, tablet computers, etc. Further, because each liquid crystal lens or each liquid crystal layer is located at a different position in the imaging system, the propagation behavior of the two components of the polarized light is not exactly the same, which can reduce the imaging quality of the system.
The disclosed methods and systems are directed to solve one or more problems set forth above and other problems, including how to directly generate high quality images with the liquid crystal lens without the polarizer and to reduce the thickness of the lens structure at the same time.